1. Field of the Invention
The present invention relates to an image forming method and an image forming apparatus for use in a printer unit and a facsimile unit including a recording head as recording means.
2. Description of the Related Art
In general, ink thermal dye sublimation printers that print image information on a sheet of chemically treated recording paper using a thermal transfer ribbon have a recording head and a platen roller. The platen roller presses the sheet against the recording head when an image is formed. In the recording head, a plurality of heating elements are arranged in a line and a plurality of the lines are arranged in parallel. The heating elements are selectively heated on the basis of image information so that ink on the ink ribbon sublimes and the image information is transferred to a recording surface of the sheet. Thus, a print operation is performed.
In this structure, the sheet transport mechanism includes a powered feed roller and a cooperating presser roller. The two rollers pinch the sheet and pull the sheet through to transport the sheet. In general, such a transport mechanism is disposed upstream or downstream of the recording head. During recording, the transport mechanism pinches the sheet to support the sheet at all times. Technology associated with such a mechanism is described in, for example, Japanese Patent Laid-Open No. 08-108590. Additionally, for color printing, one color print operation is performed once per transportation of the sheet. By driving the feed roller in a clockwise direction or in a counterclockwise direction, a different color ink is printed one on top of the other. Thus, a color image is formed.
However, as discussed in Japanese Patent Laid-Open No. 08-108590, since the transport mechanism of known thermal recording printers is disposed either upstream or downstream of the recording head serving as recording means, the following problem occurs.
Since, during recording, the transport mechanism pinches the sheet to be recorded upon by the recording head to feed the sheet at all times, a space for griping the sheet must be provided at the recording start edge and the recording end edge of the sheet. Accordingly, a margin is provided at the leading edge and the trailing edge of the sheet in the feed direction. Since these areas are unprintable areas, the entire surface of the sheet cannot be used.